Definition

A high red blood cell count indicates there are too many red blood cells circulating in your bloodstream. Red blood cells (RBCs), also called erythrocytes, are produced in your bone marrow and transport oxygen from your lungs to tissues throughout your body. A high red blood cell count is also called erythrocytosis (uh-rith-roh-sie-TOE-sis).

The threshold for a high red blood cell count is somewhat different from one medical practice to another. A high red blood cell count is generally defined as more than 5.72 million red blood cells per microliter (mcL) of blood for men and 5.03 million per mcL for women. In children, the threshold for high red blood cell count varies with age and sex.

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